Codeforces Round #275(Div. 2)-C. Diverse Permutation

http://codeforces.com/contest/483/problem/C

C. Diverse Permutation

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

Permutation p is an ordered set of integers p1,   p2,   ...,   pn, consisting of n distinct positive integers not larger than n. We'll denote as nthe length of permutation p1,   p2,   ...,   pn.

Your task is to find such permutation p of length n, that the group of numbers |p1 - p2|, |p2 - p3|, ..., |pn - 1 - pn| has exactly k distinct elements.

Input

The single line of the input contains two space-separated positive integers n, k (1 ≤ k < n ≤ 105).

Output

Print n integers forming the permutation. If there are multiple answers, print any of them.

Sample test(s)

input

3 2

output

1 3 2

input

3 1

output

1 2 3

input

5 2

output

1 3 2 4 5

Note

By |x| we denote the absolute value of number x.

解题思路：形如1,n,2,n-1,3,n-2.....这样肯定是最优的，但题目要求你正好有k个不同的，那么可以构造出k-1个不同的之后根据k是否为偶数进行单调输出

 1 #include <stdio.h>
 2 #include <string.h>
 3 #include <stdlib.h>
 4 
 5 int main(){
 6     int i, k, n, left, right;
 7     while(scanf("%d %d", &n, &k) != EOF){
 8         left = 1; right = n;
 9         for(i = 1 ; i <= k; i++){
10             if(i&1){
11                 printf("%d ", left++);
12             }
13             else{
14                 printf("%d ", right--);
15             }
16         }
17         if(k&1){
18             while(left < right){
19                 printf("%d ", left++);
20             }
21             printf("%d ", left);
22         }
23         else{
24             while(left < right){
25                 printf("%d ", right--);
26             }
27             printf("%d ", right);
28         }
29     }
30     return 0;

31 }